Xen FAQ Drivers, Windows
What are the GPLPV Drivers and where can I get them?
A collection of open source Window PV drivers that allow Windows to be para-virtualized. They are currently being implemented under the leadership of James Harper. More information on these drivers at:
How can I tell if the GPLPV Drivers are loaded correctly?
If the drivers are installed correctly there should be a Xen device under 'System Devices' in device manager.
Can I get signed GPLPV Drivers?
Yes, you can get signed GPLPV drivers from univention.de.